Tolkien’s character Eärendil was inspired by the Old English name Éarendel.
Tolkien encountered the name in the Old English poem Crist, where a passage addresses Éarendel as a bright morning star. The name made a strong impression on him and became one of the earliest seeds for his mythology. In Tolkien’s legendarium, Eärendil is a mariner who travels into the West carrying a Silmaril.
Eärendil’s story connects several major strands of Middle-earth’s history. He is the father of Elrond and Elros, and his voyage helps lead to the intervention of the Valar against Morgoth. The light of his Silmaril is later associated with the star seen by characters in The Lord of the Rings.
The character’s name appears in several forms across Tolkien’s languages and texts, including Eärendil and the Old English-inspired Éarendel. That linguistic relationship is why the question is about inspiration rather than claiming the two figures are identical.